Sunday, September 14, 2008

A new catalyst makes it feasible to split water with solar power. The catalyst enables the electrolysis system to function efficiently at room temperature and at ordinary pressure. Like a reverse fuel cell, it splits water into oxygen and hydrogen. By recombining the molecules with a standard fuel cell, the O2 and H2 could then be used to generate energy on demand. The MIT discovery could help transform electricity generated through solar energy into a fuel, making it more competitive with fossil fuels.

The key advancement in Nocera's Science paper is the development of an oxygen-producing catalyst made of cobalt and phosphate. Splitting water requires two half-reactions, one to create oxygen gas and the next to create hydrogen.

The new catalyst is remarkable because its made of common materials and can operate at room temperature and normal pressure. Without the need to heat and pressurize the water, the energy needs and cost of running the process overall are much lower.

It's important to note that Nocera's breakthrough is in making it cheaper and simpler to split water by electrolysis. Expensive machines have long been able to do the same thing, but only by using iridium alloys or exotic nanoparticles.

And whether or not the setup will prove cost-effective remains to be seen. It still uses a platinum catalyst to produce hydrogen, for example.

Erik Straser, a leading clean technology investor with the venture capital firm, Mohr-Davidow, termed the technology "promising," but said the new paper didn't shed light on its economic viability.

If this could dramatically reduce the cost of creating hydrogen, it would make hydrogen a much more viable way to store energy (either for cars or as a energy storage backup for homes) and a new way to create sustainable artificial fertilizer. It isn't clear to me how much energy is lost in the conversion and if the loss is low enough to make it worthwhile. My guess is that using batteries to store the solar power will still be the better bet, but if more breakthroughs like this were to happen that could change.